Film-developing tank



g- 12, 1952 R. G. MILLER, JR 2,606,485

\ FILM-DEVELOPING TANK Filed June 24, 1949 IO H ' 1 I lllllll I l A Patented Aug. 12, 1952 UNITED STATES PATENT OFFICE 2,606,485 FILM-DEVELOPIN G TANK Roy G. Miller, Jr., Sea Cliff, N. Y.

Application June 24, 1949, Serial N 0. 101,180

1 Claim. 1

It is the principal object of my invention to provide a tank for developing photographic film which is particularly adapted for use by amateur photographers.

I have found that developing tanks heretofore provided for use by amateurs, i. e. adapted for the development of a single film and to be handled in daylight, after the film has been introduced into the tank in the darkroom, require the exercise of a considerable amount of skill in the introduction of the film into the tank. Even a practiced and skillful workman frequently encounters difficulties which result in damage to the film such as fingerprints and scratches.

A more particular object of my invention therefore is to provide a developing tank which requires a minimum of handling of the film and a minimum of skill and practice for the introduction of the film into the tank.

Specifically, an object of my invention is to provide a tank which does not require any threading or winding of the film over or through a supporting structure or any folding or doubling of the film.

A further object of my invention is to provide a flexible tank which can be collapsed and rolled or folded into a small space for storage or transportation and which is strong and durable and unlikely to be destroyed or damaged by accident or rough treatment.

A further object of my invention is to provide a tank which is easy to clean.

A further object is to provide a tank which facilitates the handling of the developing and fixing solutions.

Other incidental objects and/or advantages of my invention will appear from a consideration of the following detailed description of an embodiment of my invention, illustrated in the accompanying drawings, and its mode of operation.

In the accompanying drawings:

Fig. 1 is a vertical section of the tank with its light-tight cover and supporting bracket;

Fig. 2 is an enlarged section of the upper edge of the tank;

Figs. 3 and 4 are a bottom plan view and a vertical cross-section respectively of the lighttight cover;

Figs. 5 and 6 are a top plan view and edge elevation respectively or the tank supporting bracket;

Fig. 7 is a fragmentary section of a modified construction of the tank edge and cover; and

Fig. 8 is a side elevation of the collapsed and partly rolled up tank.

Referring to the drawings, I is the tank formed of a flexible liquidand light-tight sheet material such as polyethylene 'or other suitable synthetic resin suitably colored or pigmented to render it opaque. The wall of the tank must be sufficiently strong and inelastic to support the weight of the solution. Relatively thick natural or synthetic rubber might be used but I prefer to use a relatively non-elastic but flexible synthetic resin such as the polyethylene or vinyl resins or if an elastic material such as rubber is used I prefer to reinforce it with fabric. It will be apparent also that waterproof coated fabric may be used and in fact any sheet material Which is lightproof, liquid-tight, sufliciently strong to hold the film treating solutions without excessive stretching, suiiiciently flexible to be rolled or folded and resistant to the chemical action of the film treating solutions.

The tank may be constructed in various ways so as to be closed at its lower end and open at its upper end and provided with a more or less rigid ring or bead surrounding its upper end for supporting it. For instancathe lower end of the tank may be molded to hemispherical shape as shown in Fig. 1 or the walls of a thermoplastic tube may be simply heat-sealed or welded together toclose the lower end. The edge of the upper end of the tube may be turned around the rigid ring 2 and welded to form the bead 3 as shown in Figs. 1. and 2 or the edge of the tube may be laid over the channel-shaped ring I! (see Fig. 7 and secured thereto by means of the ring l6 pressed into the channel. The latter construction has the advantage that the tube wall is not worn or abraded by being rubbed by the cover [5.

The mouth of the tank and the opening 5 in the bracket 4 may be of anysuitable shape, e. g. circular, rectangular, oval, etc., but since the flexible wall of thetank tends to assume a circular cross-sectional shape when the tank is filled with liquid I have made the mouth of the tank circular as illustrated. An advantage of the circular shape is that it permits the cover 8 or [5 to be rotated to agitate the film suspended therefrom in the solution in the tank while keeping the cover in position to exclude light and, as stated above, the mouth construction illustrated in Fig. 7 has the advantage that the tank wall atthe mouth is not worn or abraded by the rotation of the cover I5.

The tank may be of any desired size but for amateur photography I have found a tank about 40 inches long and about 2.5 inches in diameter to be satisfactory. I have further found a normally fiat tube formed of polyethylene resin .006 inch thick to be satisfactory. The rings 2, l6 and I! may be made. of polyethylene orother synthetic resin, wood, metal or other suitably rigid and strong material.

The bracket may be made of any suitable material, preferably a non-corrodible material such as stainless steel or synthetic resin, and has a horizontal portion't'withthe opening 5 of the proper size and shape, e. g. circular and 2.5 inch diameter, to receive and support the tank with the bead 3 or the ring I! resting on the portion 4. The vertical portion 6 of the bracket is provided with openings I for securing the bracket to a wall or, other support and preferably is secured to the darkroom wall at a height that will permit the lower end of the tank to rest on.

The-cover l5 ofFig. Tis-similar tothe. covers? of Figs; 1, 3,and 4-excepting that th'e'groove, I la" between theridges 9. and Ill is soshaped that thecoyerrests "on theouter edge of the ring I T and does not rest'upon or touch the wall of the tankln" Whenthe tank is not "in 'useitimay be removed frompthe-bracketj, 6 and foldediorrolled up as shown-in'Fig. S'to occupy -a;,relatively small space. In use thetankisidropped through the. opening 5 in the horizontal portion 4 ofthe bracket with thebead-3 or;ring l'I-resting onthe part 4 and filled with thedesired-treating solution, e; g. developer; fixerorshortst'op: In this connection I wish-tonote that in theuse of the-tank it' is preferable: to have two: tanks, one. for developer and onegfor'fixer,withasimpletray for the short stopyas'will be explained below: A film clip I3 is appliedtoon'e end-ofthefilm 14' to facilitate handling and to-weightit soithatxitwill' hang straight inv the tank: A secondfilmclip I3is then applied to the other endiof theifilm* and secured to" theloop" l2" on" the cover. The film is'then"droppedjintothe tank'until the cover rests on'the bead 3 ortheiring'l'l; Aftera suite able time in thedeveloper' the filmiis 'lifted with the cover, passed through theshort stop' in the tray referred to and then' dropped into another tank containingthe fixer.

It is: possible with-the described arrangement of two-tanks"ajnd atray for-the developer; fixer and short stop, -respectivel gi.tov carry out the development of film without having to fill the tank first'with' one solution and then with another although his of" course possible to uses. single tank for -all three of the'customary. developing operations by "exchanging solutions; It

is possiblejbut'not-practical to usethree tanks, one being forthe short stop but since'the short.

stop solution is goodfo'ronly one time whereas the developer'and fixer may be savedand used;

repeatedly over a" long period: of: time with occasional additions of replenisher 'it is preferable to use the two tanks for the developer. and fixer and a tray, say 8 by 10 inches;.for*the short stop.

It is noted that -the:film need not be; removed,

from the cover in transferringitfromonetank to another but may be transferrediwith' thecover and further that the film'rtreating "liquid in the not necessary tofilland empty the; tanks through light-tight openingsjas has been necessary with some. of the 'tankist'r'uctures' heretofore proposed.

4 Also, the need fo drying of the film-supporting structure before the film is introduced is avoided. The filling of the tanks from bottles of solution and the return of the solution to the bottles for storage also is avoided because the solutions may be stored in the tanks between successive developing operations. The tanks of my invention are practically as good as bottles for the storageof'the solutions because the area of the solution exposed to the air and the amount of air in the tank are relatively small. For the average darkroom worker the tanks will need to be emptied and refilled with fresh solution only a few times each year and when this is done the tanks may be turnedinside out to facilitate cleaning.

The use ofjtwostanks for the developer and hangingthem back to beckon the support 12.

Iclaim:

A photographic. filiIlr-dGVElOQiDEi' apparatus consisting of atubular. tank the'depth ofwhich is at least equal to the length of. film to be developedl therein and acover for said tank,.said tankv consistingof flexible sidewalls adapted to be distended to form atube and tobe collapsed and rolled into a compact bundle, said side walls being. unitedatone end. to closeone endof. the tube, thesidewalls at theother endof. the tube being joinedto a. rigid ring of larger external diameter. than said. tube whereby said. tube is provided. with an open mouth at said-other end, said ring being adapted to restona bracket and thereby. to supportsaid tube and itscontents, and said cover having;an annular. groove in one face thereof adapted. to. fit over: saidring and thereby. to close said'mouth, the inner wall of said groove extending downwardly.asubstantial distance. below. said ring and-being adapted to engagesaid bracket-l through said. flexible side walls and. thereby. toprevent lateral movement oisaid cover andsaid ringwith respect to said bracket. l ROEfG. MILLER, JR.

REFERENCES crren V The following references-are of record in-- the file of this patent:

UNITED STATES PATENTS- 

